The following enables support for running SeaBIOS as the virtual BIOS in a Xen HVM (fully-virtualised) guest.
In this series SeaBIOS is loaded by hvmloader (the Xen early firmware) rather than directly as was previously tried. This approach turned out to be far less intrusive on the SeaBIOS side and leaves knowledge of the virtual hardware setup encapsulated within hvmloader which is updated in lock step with the hypervisor and associated tools.
BIOS tables are built by hvmloader and passed to SeaBIOS via a simple in memory data structure. The tables are identified by scanning for their signatures which is hopefully extensible enough but the core structure can also be extended as necessary.
The associated hvmloader series was only posted on xen-devel can be found at: http://marc.info/?l=xen-devel&m=130692187111154 the most interesting patch is probably: http://marc.info/?l=xen-devel&m=130692182011054